Directly blow-formed bottles, in general, have body walls that are rich in flexibility and enable the contents to be easily discharged upon being squeezed. Therefore, they have been widely used as plastic containers for containing a variety of kinds of contents such as foods through up to cosmetics, hair-care products (shampoo, rinse, etc.) and the like products.
Here, to enhance commercial values of the plastic containers, means has been employed to impart an appearance of a metallic tone to them. However, imparting the metallic tone is limited to such expensive products as containers for cosmetics and the like.
That is, the appearance of metallic tone can be imparted to the plastic containers by such a method as spraying a metal pigment to form a coating of the metal pigment on the outer surfaces of the containers or a method of forming a shrink film by gravure printing a metal pigment, and covering the outer surfaces of the containers with the shrink film. According to the above methods, however, the coating must be applied for each container or the shrink film must be applied for each container greatly increasing the cost. Therefore, the above methods could not be practically applied to inexpensive containers for containing, for example, hair-care products.
In order to inexpensively impart metallic appearance, for example, a patent document 1 is proposing a master batch system in which a master batch is formed by kneading a flaky metal pigment into, for example, a resin, and directly blow-forming the resin blended with the master batch into a bottle so as to be provided with a layer that is decorated with the metal pigment. The master batch system is capable of imparting metallic appearance more inexpensively than the above-mentioned spray-coating method or the shrink film method. In this case, however, the metallic appearance is not sufficient, and it has been desired to further improve the metallic appearance.
Besides, with the above shrink film system, the containers are limited to those having straight body walls or to those of the shapes close thereto.
Further, the present applicant has previously proposed a multilayered directly blow-formed bottle having a metallic layer of a resin in which a metal pigment of an average thickness of not more than 1 μm is dispersed, the metallic layer being formed at a position where it can be seen from the outer surface side (Japanese Patent Application No. 2014-172762). For the multilayered directly blow-formed bottle, a metal pigment having an average thickness of as very small as not more than 1 μm is used to impart the metallic appearance. Though this expresses a high degree of metallic appearance, it has been demanded to realize a more increased degree of metallic appearance.